Sulfonic acid bleaching process



nitecl tates idaten 2,827,484 Patented Mar. 18, 1958 sULFoNIc Acm nrnaoimso rnocnss No Drawing. Application February 17, 1956 Serial No. 566,111

7 Claims. (Cl. 262-5435} This invention is directed to a process for improving the color of aliphatic hydrocarbon substituted benzene sulfonic acids. More specifically, the invention is directed to a process for bleaching aliphatic hydrocarbon substituted benzene sulfonic acids with hydrogen peroxide under specifically defined conditions.

In conventional processes for the production of aliphatic hydrocarbon substituted benzene sulfonic acids, products are often obtained which produce dark colored solutions. In a number of uses for the aliphatic hydrocarbon substituted benzene sudfonic acids, for example, in shampoos or as textile assistants, this dark color constitutes a disadvantage, primarily in that the appearance of the products is adversely afiected.

The bleaching of sulfonates for improvement of color is a well-known art. Generally, the procedures for bleaching of aliphatic hydrocarbon substituted benzene sulfonic acids involve treatment or" their sodium salts in the form of aqueous solutions with sodium hypochlorite.

An object of the present invention is to provide an eflicient and economical process for bleaching aliphatic hydrocarbon substituted benzene sulfonic acids with hydrogen peroxide. Other objects and advantages of the invention will be apparent from the following description and examples.

We have discovered that aliphatic hydrocarbon substituted benzene sulfonic acids may be effectively bleached in a bleaching medium consisting of a low amount of hydrogen peroxide and a certain, minimum amount of water diluent. The bleaching operation is carried out by treating the sulfonic acid with not more than about 1% of its weight (100% basis) of hydrogen peroxide in the presence of at least about 8% of its Weight of water. Stated otherwise, the low amount of hydrogen peroxide, is, according to the invention, effective in aqueous hydrogen peroxide solutions containing not above about 11.5% by Weight of hydrogen peroxide. With aqueous peroxide solutions of higher concentrations, the peroxide fails to efiect satisfactory bleaching of the acid and, in some instances, even results in darkening of it.

This hydrogen peroxide bleaching process has the advantage over hypochlorite bleaching processes in that it produces solutions having a lighter color and avoids introduction of inorganic salts which are undesirable in many cases. Further, by treating the free acids of the aliphatic hydrocarbon substituted benzene sulfonic acids, instead of their sodium salts, in the presence of the specified minimum quantity of Water, the hydrogen peroxide requirements are greatly reduced.

Thealiphatic hydrocarbon substituted benzene sulfonic acids which may be bleached by the process of the present invention include benzene sulfonic acids substituted with aliphatic hydrocarbon radicals containing up to about 23 carbon atoms. Among such substituted benzene sulfonic acids are those derived from dodecylbenzene, longchain polyalkylated benzenes (by-product from manufacture of dodecylbenzene), keryl benzenes (keryl represents a mixture of alkyl groups generally containing from 12 to 16 carbon atoms) and toluene.

The hydrogen peroxide, employed as bleaching agent in the present invention, may be introduced as an aqueous solution in which the hydrogen peroxide constitutes about 1 to by weight of the solution. The amount of hydrogen peroxide employed in practice of the invention is only from about 0.1 to about 1% (100% basis) based on the substituted benzene sulfonic acid being treated. Preferably, a hydrogen peroxide concentration of about 0.2 to about 0.5% (1G0% basis) based on the sulfonic acid is employed.

In place of the hydrogen peroxide solution, any solution which produces hydrogen peroxide under the bleaching conditions of the present invention may be employed. For example, a solution containing a metal peroxide such as sodium peroxide and an acid such as sulfuric acid may be suitably used.

in order to attain the desired results of the present vention, the presence of a quantity of water at least about 8% by weight of the sulfonic acid being treated is required. Part or all of the water requirement may be satisfied by the water present in the aqueous hydrogen peroxide solution added as bleaching agent. irrespective of the manner of water addition, the final aqueous peroxide solution will not contain more than about 11.5% by weight of hydrogen peroxide. Generally speaking, amounts of Water as high as about 390% by Weight of the initial sulfonic acid may be employed. with aliphatic hydrocarbon substituted benzene sulfonic acids which are primarily oil-soluble, such as those derived from long-chain polyalkylated benzenes, it is preferred to maintain the water concentration as close to the specified minimum as possible.

We have found that particularly outstanding results have been obtained by using about 8% to about 15% of Water by weight of the sulfonic acid being treated. This range of water permits effective bleaching, causes no mechanical difiiculties such as gelling of the sulfonic acid and does not dilute the sulfonic acid to a possibly corrosive range.

We have also discovered that part or all of the Water diluent required for successful operation of the bleaching process of the present invention may be replaced by alcohols containing from 1 to 3 carbon atoms per molecule. Particularly suitable alcohols include methanol, ethanol, isopropanol and ethylene glycol. Use of these diluents is particularly advantageous when treating terials such as dodecyl'oenzene sulfonic acid since they are often used in procedures for the extraction of dodecylbenzene sulfonic acid from suifonation reaction products.

The bleaching procedure of the present invention is generally carried out at temperatures ranging rom about 20 to 85 C. Particularly outstanding results have been obtained at temperatures of about to 65 C. After addition of the hydrogen peroxide, the ultimate bleaching desired is attained by aging the treated solution at a temperature of about 30 to C. for about /4 hour to about 3 hours. However, if desired, a shorter or longer aging period can be used.

When the aliphatic hydrocarbon substituted benzene sulfonic acid is prepared by an oleum or sulfuric acid sulfonation, the resulting product, upon standing, forms two layers, the top layer comprising mainly the sulfonic acid and the bottom layer comprising mainly sulfuric acid. it is a feature of the present invention that when used in conjunction with a sulfonation process which yields spent sulfuric acid, the spent sulfuric acid layer as Well as the sulfonic acid layer are both bleached. This is of economic importance since the spent sulfuric acid layer may then be employed for other uses where color is an important consideration.

" The present invention may be illustrated by the following examples in which parts are by weight:

EXAMPLE 1 Dodecylbenzene sulfonic acid was prepared byjthe continuous sulfonatiori of dodecylbenzene with-vaporized sulfur trioxide 'mixed with diluent air. This sulfonic acid wastreated with 2% by weight of water to convert any anhydrides present to the corresponding acids in accordance wtih the process of Carlson et-al. application Serial No. 456,062, filed September 14, 1954.

100 part samples of the treated sulf onic acid (98% concentration) were then diluted further with varying amounts of Water at 50 to 55 C. 0.75 part of 30% hydrogen peroxide solution (0.225 part'of hydrogen peroxide on 100% basis) was added to each sample (except a'blank) with stirring. The samples were then aged at temperatures varying from 50to'55 -C. for about 1 to 2 hours.

The resultant bleached solutions were neutralized by addition of'dilute aqueous caustic soda solutionito form 10% by weight solutions of dodecylbenzene sodium sulfonate. Comparative colors were then determined on a Klett-Summerson photo-electric colorimeter, test tube model, using No; 42 'blue filter, a lower number corresponding to a lighter color. Datafor these tests are summarized in Table I'below:

Table l Total Water Present Temperature, 0. Color Water Added (Percent by Wt. of 7 (After (Parts) Sulfonic Acid) Neutral- Bleaching Agmg ization) 2.0 (no H302 added) 50-55 50-55- 322 2.6 50-55 50-55 440 50-55 50-55 153 50-55 50-55 135 50-55 50-55 137 Blank.

As shown by the above table, the addition of 30% hydrogen peroxide solution without prior dilution with water actually resulted in a darker product instead of bleaching.

EXAMPLE 2 Tests were carried out by procedure similar to that of Example 1, using 100 parts of 99.5% dodecylbenzene sulfonic acid and varying amounts of water. In each test (except a blank) the amount of hydrogen peroxide con-i stituted about 0.3 part (100% basis). The-data for these tests are summarized in Table 11 below:

Blank.

These tests emphasize the criticality of the concentration of. waterrequired by the process of the present invention.

' 7 EXAMPLE 3 'Tests were carried out in accordance with the procedure of Example 1,- using 100 parts of 98% .dodecylbenzene sulfonic acid (preparedas in'Example 1) and varying strengthsof hydrogen peroxide; (except: a blank). the amountoi hydrogen peroxide 0011;.

In each test stituted about 0.225 part basis). The data for these tests are summanz' ed in Table III below:

Table III Hydrogen Total I Temperature, Water Peroxide Water 0. Color Added Present (After Prior to (Percent 7 Neutral- Peroxide Strength by Wt. Bleachization) (Parts) (Percent) Parts Sulionic iug Aging Acid) V i Blank.

These tets show that the strength of the peroxide added is immaterial as long as the required amounts-of Water and peroxide are present. Further, the tests'showthat the water diluent may be added simultaneouslywith the hydrogen peroxide (instead of before, as in Examples- 1and2).

EXAMPLE 4 Tests were carried out in accordance with the procedure of Example 1, usingv 100 parts'of 98% dodecyl benzene, sulfonic acid (prepared as in Example 1) and, varying quantities of 15% hydrogen peroxide solution.

The data for these tests are summarized in Table IV;

below: r

' Table IV Hydrogen Total Water Peroxide Water Temperature, 0. Color 1 Added (Parts) Present (After- Prior to (Percent V I N entrai- Peroxirle by Wt. ization), (Parts) Gross Net Sulionic Bleaching Aging Acid) Blan k. 7

The tests of this example show. that thebest improves.

ment .inreduction of color ,of :dodecylbenzene sulfonic acid occurs when thequantity of hydrogen peroxide used:

compiises at least about; 0.3 part--.( 100% basisl'per 100. parts of dodecylbenzene sulfonic acid.

EXAMPLE 5 Dodecylbenzene was sulfonated batchwisewith sulfur trioxide vapor. The resultant sulfonic acid was treated.

with 2% by weight of water to convert any anhydrides present to the corresponding acids.

100 parts of the 98% sulfonic' acid were then treated. with 8 parts water and 3 parts of 10% hydrogen peroxidev The initial sulfonicacid, after neutralizationtoa 10% 1 solution with dilutezcaustic'sodagsolutiomgave a color of 236 on the .Klett-Summerson photo-electric calorimeter,- while the hydrogen peroxide-treated sulfonic acid, after.

neutralization to a 10% solution, gave a color-of 63.

. EXAMPLE 6 Part A.-.1 part of 3.0% hydrogen peroxide solutionwas. added .to a mixture of-42 parts of dodecylbenzene sulfonic acid and: 37mm of 96% sulfuric acid at room temperature. The, quantity of hydrogen peroxide2 used was 0.7% (100% basis) by Weight of the sulfonic acid, and the total water present Was about by weight of the sulfonic acid and about 2.5% by weight of the sulfonic and sulfuric acids. Immediately, the mixture became darxer and remained so on standing at room temperature.

Par: B.A mixture of 42 parts of dodecylbenzene sul tonic acid and 37 parts of 96% sulfuric acid was treated with 15 parts of water and allowed to cool to room temperature. Then, 1 part of 30% hydrogen peroxide solution was added. The quantity of hydrogen peroxide used was 0.7% (100% basis) by weight of the sulfonic acid, and the total water present was 41.5% by weight of the sulfonic acid and 19.5% by weight of the sulfonic and sulfuric acids. The mixture immediately became lighter. Upon standing, two layers formed, the top layer comprising primarily the sulfonic acid and the bottom layer comprising primarily sulfuric acid. Both layers were amber in color, being substantially lighter in color than before the treatment with hydrogen peroxide.

EXAMPLE 7 Toluene sulfonic acid was prepared by the direct addition of liquid sulfur trioxide to toluene. The resulting product contained about by weight of ditolyl sultone.

Parr A.-50 parts of the toluene sulfonic acid were treated with 1 part of 30% hydrogen peroxide solution at 30 C. The quantity of hydrogen peroxide used was 0.6% (100% basis) by weight of the sulfonic acid, and the total water present was about 1.5 by weight of the sulfonic acid. The treated sample was allowed to stand overnight, diluted with 449 parts of Water and filtered to remove insoluble sulfone. The filtrate was tested for color on the Klett-Summerson photo-electric colorimeter and was found to be 330.

Part B.50 parts of the sulfonic acid, treated as in part A but in the absence of hydrogen peroxide, exhibited a color value of 350, indicating that little bleaching was effected by the hydrogen peroxide treatment.

Part C.50 parts of the sulfonic acid were first treated with 5 parts of water and then with 1 part of 30% hydrogen peroxide solution at 30 C. The quantity of hydrogen peroxide used was 0.6% (100% basis) by weight of the sulfonic acid, and the total water present constituted 11.5% by weight of the sulfonic acid. Dilution and color determination as in part A gave a value of 242, showing that considerable bleaching had taken place.

EXAMPLE 8 2 parts of distillation residues, obtained as a by-prodnot in the manufacture of dodecylbenzene detergent alkylate, were diluted with 1 part of Procoil A (a highly solvent-extracted petroleum lubricating oil) and were then sulfonated with sulfur trioxide vapor.

Part A.-50 parts of the resultant sulfonic acid, after dilution with 6 parts of water and 16 hours aging at room temperature, was diluted with a solvent comprising 50% hexane and 50% isopropanol at a dilution ratio of 16 parts of solvent mixture to 1 part of sulionic acid. A color value of 825 on the Klett-Summerson photo-electric colorimeter was obtained.

Part B.50 parts of the sulfonic acid were treated with 1 part of 30% hydrogen peroxide solution at room temperature. The amount of hydrogen peroxide used was about 0.9% (100% basis) by weight of the sulfonic acid, and the total water present constituted about 1.5% by weight of the sulfonic acid. The treated sulfonic acid was then diluted and its color determined as in part A. A value of 640 was obtained, showing that very little bleaching had occurred.

Part C.50 parts of the sulfonic acid were treated with 5 parts of Water, then with hydrogen peroxide solution in the same manner as in part B. The amount of hydrogen peroxide used was the same as used in part B, and the 0 total water present constituted about 11.5% by weight of the sulfonic acid. After dilution as in part A a color of 282 was obtained.

EXAMPLE 9 meter. The following results were obtained:

Table V Total Water+ Temperature, 0. Color Water Alcohol Alcohol Present (After Added Added (Percent by Neutral- (Parts) (Parts) Weight of Bleaching Aging ization) Sulionic Acid) 0 0 0.5 (no H202 about 40 -40 (2% 530 Hrs). 0 630 0 175 1 5 166 1 10 195 10 150 1 Isopropanol. 2 Methanol. Blank.

The above tests illustrate that alcohols containing from 1 to 3 carbon atoms per molecule may be substituted for the water employed in the bleaching process of the present invention.

EXAMPLE 10 below.

Table VI Total Water Temperature, 0. Water Ethanol and Ethanol Color Added Added Present (After (Parts) (Parts) (Percent by N eutral- Weight of Bleaching Aging ization) Sulfonic Acid) 0 0.5 (no 11202 about 40 3040 (2 650 added) 1 h 1 2.2 650 4 440 10 250 Blank.

The above tests show that approximately the same quantities of alcohol as water are required for effective sulfonic acid bleaching.

Since various changes and modifications may be made in the invention without departing from the spirit thereof, the invention is deemed to be limited only by the scope of the appended claims.

We claim:

1. A process for breaching a benzene sulfonic acid substituted with an aliphatic hydrocarbon radical containing up to about 23 carbon atoms which comprises treating said acid at a temperature of about 20 to 85 C. in a bleaching medium consisting of hydrogen peroxide and at least one member of the group of dilucnts consisting of water and alcohols containing from 1 to 3 carbon atoms per molecule, the amount of hydrogen peroxide being about 0.1% to about 1.0% by weight (100% basis) of the acid :7 r and the amount of diluent being at least about 8% by weight of the acid. r a

2. A process for bleaching a benzene sulfonic acid sub- 'stituted with an aliphatic hydrocarbon radical containing up to about 23 carbon atoms which comprises treating said acid at a temperature of about 20 to 85 .C. in a bleaching medium consisting of hydrogen peroxide and water, the amount of hydrogen peroxide being about 0.1% to about 1.0% by weight (100% basis) of the acid and'the amount of water being at least about 8% by weight of the acid.

3. A process for bleaching dodecylbenzene sulfonic acid which comprises treating said acid at a temperature of about 20 to 85 C. in a bleaching medium consisting of hydrogen peroxide and water, the amountof hydrogen peroxide being about 0.1% to about 1.0% by weight (100% basis) of the acid and the amount of water being at least about 8% by weight of the acid.

4. A process for bleachingdodecylbenzene sulfonic acid said acid at a temperature of about 20 to 85 C. in a bleaching medium consisting of hydrogen peroxide and water; the amount of hydrogen peroxide being about 0.2% to about 0.5% weight (100% basis) of theacid' and the amount of water being about 8% to about by weight of the acid. a y a r 6. A process for bleaching dodecylbenzene sulfonic acid which comprises treating said acid at a temperature of about to C. in a bleaching medium consisting of hydrogen peroxide and water, the amount of hydrogen peroxide being about 0.2% to about 0.5% 'by Weight basis) of the acid and the amount of water being about 8% to about 15 by weight of the acid.

7. A process for bleaching dodecylbenzene sulfonic acid which comprises treating said acid at a temperature of about 20 to 85 C. in a bleaching medium consisting of hydrogen peroxide and an alcohol containing from 1 to 3 carbon atoms per molecule, the amount of hydrogen peroxide being'about 0.2% to about'0.5% by weight (100% basis) of the acid 'and'the amount of alcohol being about 8% to about 15 by weight of the acid.

References Cited in the file of this patent UNITED STATES PATENTS 1,842,884 Taylor Jan/26, 1932 2,049,975 Reichert et a1. Aug. 4, 1946 2,524,056 Jespersen Oct. 3, 1950 

1. A PROCESS FOR BLEACHING A BENZENE SULFONIC ACID SUBSTITUTED WITH AN ALIPHATIC HYDROCARBON RADICAL CONTAINING UP TO ABOUT 23 CARBON ATOMS WHICH COMPRISES TREATING SAID ACID AT A TEMPERATURE OF ABOUT 20* TO 85*C. IN A BLEACHING MEDIUM CONSISTING OF HYDROGEN PEROXIDE AND AT LEAST ONE MEMBER OF THE GROUP OF DILUENTS CONSISTING OF WATER AND ALCOHOLS CONTAINING FROM 1 TO 3 CARBON ATOMS PER MOLECULE, THE AMOUNT OF HYDROGEN PEROXIDE BEING ABOUT 0.1% TO ABOUT 1.0% BY WEIGHT (100% BASIS) OF THE ACID AND THE AMOUNT OF DILUENT BEING AT LEAST ABOUT 8% BY WEIGHT OF THE ACID. 